快速排序，快速排序演算法

快速排序，快速排序演算法

#include<stdio.h>#include<algorithm>using namespace std;void InsertionSort(int a[],int N){int j,p,tmp;for(p=1;p<N;p++){//1-N-1趟目標tmp=a[p];for(j=p;j>0 && a[j-1]>tmp;j--){a[j]=a[j-1];}a[j]=tmp;}}int median3(int a[],int left,int right){int mid=(left+right)/2;if(a[left]>a[mid]) swap(a[left],a[mid]);if(a[left]>a[right]) swap(a[left],a[right]);if(a[mid]>a[right]) swap(a[mid],a[right]);swap(a[mid],a[right-1]);return a[right-1];}const int cutoff=3;void Qsort(int a[],int left,int right){int pivot,i,j;//左小右if(left+cutoff<=right){//三數取中pivot=median3(a,left,right);i=left;j=right-1;//分割for(;;){while(a[++i]<pivot){}while(a[--j]>pivot){}if(i<j)swap(a[i],a[j]);elsebreak;}//換回軸樞swap(a[i],a[right-1]);Qsort(a,left,i-1);Qsort(a,i+1,right);}elseInsertionSort(a+left,right-left+1);}void main(){int a[13]={13,12,11,10,9,8,7,6,5,4,3,2,1};Qsort(a,0,12);return ;}